Production of methallyl halides



June 16, 1953 H. A. CHENEY ETAL PRODUCTION OF METHALLYL HALIDES Filed May 29, 1948 Jur wzrEzQUu lnvni'or-s: evry A ICheneg Alasdair W. Fairbair'n Orvis L .Davs

The," ornzg Patented June 16, 1953 PRODUCTION OF METHALLYL HALIDES Harry A. Cheney, Alasdair W. Fairbairn, and Orris L. Davis, Berkeley, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application May 29, 1948, Serial No. 29,966

6 Claims.

This invention relates to the production of methallyl halides. More particularly the invention relates to a method for the production of methallyl halides from isobutylene or-hydrocarbon mixtures containing the same.

More specifically the invention provides a practical and highly economicalmethod for the production of methallyl halides in large yields from isobutylene or hydrocarbon mixtures containing the same which comprises halogenating a tertiary butyl halide, preferably in a preheated condition, at a temperature above 300 C. so as to form methallyl halide and the corresponding hydrogen halide, introducing the resulting mixture, preferably after being cooled, into a stream of isobutylene or hydrocarbon mixture containing the same wherein the hydrogen halideformed in the halogenation reaction combiner vwith the isobutylene to form a tertiary butyl halide, removing the tertiary butyl halide from the reaction mixture and recycling it to the halogenation'step and recovering the methallyl halide from the reaction mixture as the desired product.

vMethallyl halides have shown promise for a great many fields of utility in industry. Their particular structural characteristics illustratedv by the following formula formethallyl chloride:l

cupo-onzer makes the said compounds especially valuable at the present time in the production of insecticides and synthetic resinmaterial. v tential uses of the methallyl halides have, however, not been exploited due to the high costs involved in their production. Various methods have been employed to produceI the desired methallyl halides but they have all met with such technical dimculties or have employed such expensive reactants and equipment, that they have proved entirely unieasible, in most cases, for the production oi the said compounds on a large commercial scale, Direct halogenation, via substitution, of isobutylene is perhaps the most direct process for the production of the methallyl halides but it has been found to have several disadvantages, the most prominent of which is the fact that the sobutylene employed in that process must be in a relatively pure form. The

most readily available source of the'isobutylene is the hydrocarbon fractions obtained from the distillation ofY petroleum and natural gas. To

-Obtain the isobutylene in a pure form from this source requires a very complicated and expensive separation process.

Many of the po- Furthermore, iny this par-y ticular direct chlorination process the isobutylene must be maintained in excess resulting in a reactor eflluent containing both isobutylene and the hydrogen halide formed in the initial reaction. Inorder to prevent these two materials from combining to form contaminating by-products the reactor eilluent must be quenched rapid- It is an object ofv the invention, therefore, tok

provide a practical and highly economical method for the production of methallyl halides. It is a further object of the invention to provide a method for the production of methallyl yhalides from isobutylene which utilizes a mixture of hydrocarbons containing the isobutylene as stock material for the process. It is a further object to provide a method for vproduction of dry HC1. It is still a furtherv object of the invention to provide a method for the production of methallyl halides from isobutylene which avoids the necessity of using expensive scrubbing towersl and corrosion-resistant equipment. It is still a further object of the invention'to provide a method for the production of methallyl halides byv the halogenation of preheated tertiary butyl halides. It is still a further object to providea method for the production of methallyl halides from mixtures of hydrocarbons containing isobutylene which does not require the use of catalysts Vor heat-removing diluents.y It is still a further object of the invention to provide a method for the production ofa methallyl chloride from iso-l butylene which yields high, relatively 'pure yieldsY of the desired product. Other objects of the invention Will be apparent 'from the detailed description given hereinafter.

It has new been discovered that these enelV othereobjects may be raccomplished by the novel method of the invention which comprises halo-Av genating a tertiary'but'yl halidepreferably in a preheated condition-'at a temperature above 300 C., preferably 350 C. to `460" C., so as to form methallyl halide 'andthe corresponding hydrogen Complete drywith the excess hydrogen halideinray bezsubjected; 175` halide, introducing the resulting mixture, preferably after being cooled, into a stream of iso-A butylene or hydrocarbon mixture containing the same wherein the hydrogen halide formed in the halogenation reaction combines with the iso- 5 butylene to form a tertiary butyl halide, removing the tertiary butyl `halide from-: .th'ereaction` mixture and recyclingy it-to the halogenation'stepi.

and recovering the methallyl halide from the reaction mixture as the desired product. It hastfli been further discovered that inthose.cases.wh.ere. the isobutylene is utilized in^ thereaction admixture with other hydrocarbonsgthe:residuali hydrocarbons recovered from theffaboveprocessf tively-pure yields-produced. by the. process, and 3()L ther adaptation of themesidual-hydrocarbon .byproducts for use .inialkylation all f tend :to: lower the cost ofthei-productioniofthe-.methallyl hal-- idesiand enable the said .compoundsto 'be vplaced onfthe rmarket: in *.suiiicientyquantities;vr for. a full. 1 exploitation of. their lmanyf uses:

Theisobutylene to be. usedinthe processrof the;.inventionmay beinV thefpurezform orin ad-A mixtureiV with; other; hydrocarbons; TheY eco nomcal features offtheipresent processl are-more: 40 in evidence; however., `when. mixtures: of. hydrocarbonss. containing 1 the;y sobutylene;A are .used ras` stock material and:they areJ the: preferred maeY terials .to.,be.usedfin the; process. of .the-invention. Examplesof; mixtures. of r. hydrocarbons which. may be 1 used' as .f stockt material fon-the.--p resent process are:those.-mixtures-.of f hydrocarbonsfob. tained. by. `a pyrol-yticr treatment `or. cracking." of.- natural gas, petroleum, petroleumiproducts,.coal tar, pitches,peat, sha-leoilv andithe like. or re- 5 latedcarbonaceousmaterial. lvlixturessof.hydro.-n carbonseobtainedfromsuch sourcesusually con-- taina.` great varietyyof; diierenttypes-of hydro carbon compounds andin manyY casestliasbeen foundadvisable to separate-:the mixture-roughly, usually; by" fractional distillatiominta-fractions4 containing; hydrocarbons;l ofL approximately the4T sameenumber; of carbon..atoms..and. to.` use vthese separate fractions' as stock .material for the :process'gof :the..-invention: In the-..rep rocluction of. they'. o methallyl halide from mixtureseof.hydrocarbons obtained fromf the.- crackinggoff petroleum,.. forVA example; ithas-1 been.v found'. advisabletof firstseparatefromf the f hydrocarbon mixture-` a: C4@ fraction containing ther desired isobutyleneA and r 65 to -use this-fraction :asfstockmaterial. for, the re.- action. In: most,I cases; however, the; fractions: used will contain othercompounds in a'dditi'onjtoisobutane, 1,3 butadiene,-i cis-.Zebutcne tand trans; 70 Z-.buteneM These-related compounds: contained within, the-*hydrocarbon fractionsshave,Y however, been found `not to `interfere;with; theproduction of the methallyl?halidesf'lcyfthe.; present process` and the isobutylene-may`v bef readily introduced.v 75

.on` steps.; Ther. first ferredfitozlas-,tlie halogenation reaction, comprises` 'th'ee-li'alogenatioirY of the tertiary butyl halide into the reaction mixture in admixture with these other hydrocarbons.

Any of the halogens may be used in the execution of the process of the invention to accompli-sh the desired halogenation. Chlorine, however, is usually preferred as it is more readily availablef andi more easilyfhandlled... Examples ofthe methallyl halidesawhich vmay be produced by the process of the invention are methallyl chloride, :methallyl bromide and methallyl iodide. The novelprocessf the invention for the production"of"the methallyl halides may be broadly describedrasconsisting of three distinct phases step, hereinafter reat: a; temperature. above 300 C. to produce the desired methallyl halide and the .respec-l tivee hydrogen halide. The next step, hereinafter referred to as the hydrohalogenation reaction; comprises treating and reacting-.j the eflluent. of: thefrstx. reaction with'. isobutylene or; mixturesicontaining it'vunder such conditions.-

thatzthef said iscbutylenefreacts.with theh drogen halide toffproducef thee. tertiary butyl halide. Theelast step-:in .the 1 process; .hereinafter referredztofaszxth'e;separation process, comprises` avseries ofi separationfiprocesses wherein the=-ex cess; hydrogen- A halide and .,unreacted hydrocar- ;bons.;contained:in the mixtur.e. are recovered and c preferably. retained-for .futureafuse in alkylation processes, the-@tertiary'butyl-.halide is recovered and: recycled-. to; thel initial halogenation step,- and; the` z methallyli halide e is.; recovered 1 in relatively pura.forrngaszthee` desired product f of theprocessi.

The frstgstep: ofi'thesprocess; i; e; the 'halogenVn ation step; is.; esseni',iaily;r at high; temperature vapor: phases rea-lotion: and isf. accoi'nplished;Y at; temperaturesaboye ,300i7 v:but-usually notv higher.

than D-f Cl In. generali temperatures; ranging frorrrabout";350"'(1.` .toLaboutiGOf C. produce very satisfactory results .andzthey` are: the; preferred temperatures'rto be-xusedzirr;theehalogenationre-` action'.

To 1 accomplish. thea. halogenation: reaction at action, etc;,` but' the` preheating temperature shouldfberso" determined* as Y"to-enable the reactioni temperature tojr be: maintained at approximately; theK requiredE level` duri-ngA the required residenceperiod Inrgeneral, preheating temperatures..Inayjvary Ibetweeny about: 300 C. to about 25; CL' belowv therequired halogenaticn reaction temperaturez but the exact preheating temperature tube usedin each instance may best'Y be `determined for :eachparticularl case;

VForl most satisfactory;resultsfin the halogen-Y ation r`eaction the .tertiary butyl halide should be maintained in molar excess of thehalogen. FeedY mol ratios of .the.ter tiary.buty1 halidetoV the halogen only slightly inexcess of 1:1.. produce satisrfactory resultsbutit;ispreferred to. maintainr the moli ratioottertiary. but'yLhalide to,..the. halogen inexcess. of.1.5.: l. Exceptionally. ne results are produced bymaintainingfthe ratios between about 2,: 1. andzabout 8:1;and.these.are the particularly preferred 1 ratioscto he.A used; in the halogenation reaction. The lower ratios and particularly those ratios than 8:1 are usually unnecessary in that` they result in negligible improvement in yield, but complicate product recovery.

In mixing the tertiary butyl halide with the halogenating agent it has been found'advisable to make use of high velocity and turbulent flow toj insure a thorough mixing of the reactants before they enter the reaction chamber. A thorough mixing may be accomplished in most instances'l by bringing the gases together at an angle under pressure. Exceptionally fine results are obtained when the reactants are brought together at an angle of about 135 with the halogen being ad` mitted as the side stream. This procedure,v

though not essential to the process, is particularly preferred as it insures a thorough, yet rapid mixing'of the two reactants and enables the resulting mixture to be carried into the reaction chamber before the halogenation reaction takes place.v

The residence time for the halogenation reaction will vary according to the ratio of reactants used, the temperature of reaction,V the particular reactants employed, and the like, but under all circumstances the reaction period should not generally exceed a few seconds. In general, the residence time may vary between about 0.1 second and 10 seconds. Reaction periods of over 10 seconds should generally be avoided. Residence periods of between about .5 and 3 seconds are usually preferred. y

Atmospheric, superatmospheric or subatmospheric .pressure may be used in the halogenation reaction. Y

In addition-to the methallyl halide the products of the high temperature halogenationY reaction will comprise the tertiary butyl halide, the corresponding hydrogen halide, small quantities of isobutylene and higher halogenated products. These products are mixed with the stock source of the isobutylene and the resulting mixtur-e is taken to the second reaction chamber to undergo ythe hydrohalogenation reaction. As the hydrohalogenation reaction is preferably conducted in the liquid phase it is preferred to cool and condense the eiiluent of the halogenation reaction so that a substantial portion is in the liquid phase before it is mixed with the stock source containing the isobutylene. The condensation may be accomplished by any suitable chemical or mechanical means suchas refrigeration and internalr cooling agents. In some cases it maybe desirable to compress the eii'luent of thehalogenation reaction to aid in condensation. I

The pure isobutylene or the hydrocarbon mixture containing it may be introduced into the stream of reaction products of the halogenation reactionA as a gas but as the hydrohalogenation reaction is to be accomplished in the liquid phase,`

it is preferred to introduce, the isobutylene or the mixture containing it in the liquid form.

YThe rate of introducing the isobutylene into the stream of reaction products of the halogenation reaction may be varied over a considerable range depending upon the concentration of the hydrogen halide in the reaction products. To avoid the production of cumbersome amounts of reaction mixture, especially in those instances where the isobutylene is beingintroduced in ajhydrocarbon fraction, it has been found'advisable to maintain the hydrogen halide in molar excess of the isobutylene. Thereaction proceeds veryy reactor, this will ordinarily result in a mole ratior Mixing of the isobutylene or mixtures containing it with the eiiiuent of the halogenation reaction need not take place before they enter the reaction chamber. The two streams may if desired be introduced separately to the hydrochlorination reaction chamber,

In the second reaction chamber the hydrogen halide contained in the effluent of halogenation reaction reacts with the isobutylene to produce the tertiary butyl halide. This hydrohalogenation reaction may be generally represented by the equation below showing the production of `tertiary butyl chloride from isobutylene:

, Y C1 H2o=o-on3 +'Ho1 Hao-clion= CIJHS H3 This hydrohalogenation reaction is an exothermic reaction producing large'quantities of heat. In some cases the reaction maybe carried out adiabatically with the' heat of reaction being absorbed by the reactor contents'. If desired heat may be removed from the reaction zone by means of internal or external cooling coils or by other methods. A f

The hydrohalogenation reaction proceeds satisfactorily at any temperature below, about 300 C. providing the reaction medium' is maintained in the liquid phase. The reaction is known to take place even at temperatures as low as 80 C. but the preferred temperatures areffrom about 40 C. to about 80 C.

The pressure used in the hydrohalogenation reaction should be at least suicient to maintain a substantial proportion of the reaction mixture in the liquid phase. Extremely high pressures such as those in excess of .700 to SDGpounds per square inch, in general', `add little to the eciency of the reaction and should be avoidedl for economical reasons. Particularly preferred pressures to ,be used in the hydrohalogenation reaction are thosebetween about 25 pounds per square inch and about 200 p. s. i.

Catalysts, promotor's or inhibitors may be einployed in the'execution of the hydrohalogenaticn reaction, if desired, but they are usually not necessary as the reaction proceeds very smoothly under the above specified conditions to produce the desired results. q Y e The residence time for the hydrohalogenation reaction will vary according to the ratio and particular type of reactants employed, and the quantity of other materials present. In general, the

residence time may vary from l0 seconds to about ride. -After mixing, the reactants-are passed into a thermally insulated tubular reactor. Here the reactants attain a temperature about 460 C. for a residence time of about 0.68 second. The

10 uct with chlorine in mole ratio of about 4 to 1 at 460 C. for a period of about 1 second, cooling and compressing the reaction mixture and 4introducing it into a stream of isobutylene at such' arate mide remains in the bottoms.

We claim as our invention:

1. A process for the production of methallyl chloride which comprises preheating tertiary butyl chloride to 390 C., reacting the resulting prodreaction products are cooled, condensed and fur- 5 that the hydrogen chloride contained in the rether cooled. A stream of liquid Ci hydrocarbons action mixture and the added isobutylene are in containing about 16.6 mole per cent isobutylene is the mole ratio of about 2 to l, allowing the rethen mixed withr the cooled reaction product. sulting mixture to-react in the liquid phrase at 40 The entrance of the liquid hydrocarbons is reg- C. vfor a period of about 55 seconds whereby isoulated so that there are about 1.24 moles of hybutylene isv hydrochlorinated yto tertiary butyl drogen chloride for every mole of isobutylene in chloride, subjecting the resulting mixture to fracthe mixture. After mixing, the reactants are tional distillation and removing the excess hypassed into a tubular reactor surrounded by a drogen chloride overhead, subjecting the bottoms water jacket. Here the reaction temperature is ofv the distillation to another fractional distillowered by means of cooling, and the reaction is lation and removing tertiary butyl chloride overallowed to take place at about 50 C. Residence head, recycling the tertiary butyl chloride to the time for the reaction is about 54 seconds, and preheating step, and recovering methallyl chloreaction of isobutylene is essentially complete. ride from the bottoms of the last fractionation. The reaction products are separated by means v2. A process for the production -of methallyl of a series of fractional distillations. The exchloride which comprises preheating tertiary bucess hydrogen chloride and residual liydrccar tyl chloride and reacting the resulting product bons contained in the C4 fraction are taken off with chlorine in mole ratio of about 4 to 1 at a overhead in separate towers. The tertiary butyl temperature 0f about 460 C-OI' la period 0f be* chloride is then taken off overhead in the third tween 0.5 second and=3`sec0nds,'coo1ng the retower. The methallyl chloride remains in the action mixture and introducing vit into vva stream bottoms and is recovered-in pure form by further of C4 hydrocarbons containing i'sobutylene at such fractionationl in a yield of 91% based on the a rate that the hydrogen chloride contained in consumptionof chlorine. the reaction mixture and the added isobutylene Other yields obtained under various conditions :are in a mole ratio of about 2 tol, treating the of operation using Ci fractions as source of iso 3f) resulting mixture in the-liquid phase at a tembutylene are shown in the following table: pelature 0f about 40 C-fI a reaction pt'iodA 0f it@ Molar Ratio Residence Molar Residence Penlgtlau ld Tertiary Chlorination Time for Ratio Temp Time for "ohlorids l Butyl Tempera- Halogenaof HC1 C Hydrohalov based on. Chloride ture, C. tion Reacto Isogenation Re- Chlorine com to Chlorine tion, Sec. butyleiie action, Sec. Sumption 3. 6 365 1. 1 1. 0s 30 10b as 2 44o 2.8 1.13 55 56 94 1.6 46o .7 1.21 so 54 96 l Example III beween about 20 and 100 seconds whereby isobu ylene is hydrochlorinated to tertiary butyl- Tei t r de a oi is ieheated to a temelul; lf antl nixed with bromine chloride .SubJect-mg the emuent of thts .hydt- Vapor in the ratio of about 3.5 moles of tertiary chlorination treatment to fractional distillationv butyl bromide per mole of bromine. After mixto remQYe me excess hydrogen Chlorlde ovrltead ing, the reactants are passed into a tubular re- 'Bind sublectmg the bottoms to' a Second dlstlua' actor enclosed in a resistance furnace. Here the mon to remov the resldual hydrocarbons over' reactants are maintained at a temperature behal and SubJectmg the bottoms o; the second tween about 400., C and about 460 C' for a resp 50 distillation to another fractional distillation to dence period of about 2 seconds. The reaction remve' the tertiary butyl Chlollde Overhead' re' products are cooled, condensed and further Wem-1g the tertlataybutyl chloride to thevpreheat cooled. A stream of liquid C4 hydrocarbons constep andrecovermg the mtha'ltyl hloride'from v taining about 16.6 moles per cent isobutylene is th; bttoms of @e lastfractlon'aiiton then mixed with the reaction'products of the 55 l proqess for* me productlqn of methauyl haiogenation reaction. The entrance of the liquid' Ch ondeWhlCh compms-es preheatmg .ternary bu' hydrocarbons is regulated so that there are about W1 chlonde atld reactmg. theresultmg product 1 5 moles of hydrogen bromide for every mole OI. with chlorine in mole ratio between about 2 to 1 iscbutylene in the mixture. After mixing, the andg about 8 to l at a.tel.npera'ture between about reactants are passed into a tubular reactor sur- 50 .300 C' and 790 CZWlthm 0'1 ,5.0 10 Seqnds c001` rounded by a water jacket. Here the reaction mg the reactlon mlxture and mtroducmg it into temperature is lowered by means of water coolA a stream of 'C4 hydrocarbons containing iSObU-tylf ing and reaction is allowed to take place at about ene ait sucjh a rate that the hydrogen Chloride 50 C. Residence time for the reaction is about ontafned m th?. reacmon mixture and the added 8d seconds. The reaction products are separated. 65 lsobubylene are im a m01@ rat/i0 0f between about v by means of a series of fractional distillations.l l to l 'and t0 1 Heating the resulting mix- The excess hydrogen bromide and the residual ture 1n the llquid Phase at a temperature of be. hydrocarbons contained with the C4 fraction are tween about *40o C- am 80 C. Within about 20` taken Off msn The tertiary butyl bromide is seconds to seconds whereby isobutylene is then taken loif overhead and the methallyl bro'- 70 hydlOChlOllIl'ftted t0 tertiary butyl Chloride, subjecting the eliiuent of the hydrochlorination treat--v ment to fractional distillation to remove the ex-r cess hydrogen chloride overhead and subjecting the bottoms to a seconddistillation to remove the residual hydrocarbons overhead and 1::1' subjectingi the.A tertiary butyl chloridefcontaining bottoms of,thefseconddistillationi to another Tractional, distillation: to remove the tertiary butyl chloride oyerhead, recycling the tertiary butyl chlorideto the-preheatstcm and recovering; the 5 methallyl` chloride `from the bottoms ofe the last fractionation. ,x v t 'process7 for. the. production of.l methallyl bromide,which cc'mipvrisesl preheating tertiarm'bu'- tyl; bromide and'. reactingI theresulting product with: bromide in molefr'atio-of between abou-t2.v to land about 8 to 1 at.. aftemneraturei between about 400i? 'Gland-55,0? C...for, arperiodof between p55 secondand- `3 seconds, cooling, the' reaction mixture; andi` introducingit into, a stream ofy C4 hydrocarbons containing, isobutylene` at such.,` a rate that the hydrogen bromide containedinthe reaction. mixture, andthe addedisobutylene are imamole ratiofbetween about-11 to 1.- and 4xto 1, reacting the resultinsrmixture; in-,thel liquidv phase. at a,,t,empe1ature.of .betweengaboutfBO C. and 50i7 G. for: a.,- resdenoe period.- 0,2y not; more: than; 200 seconds'wherebv the@isobutylenel is-rhydrobromif natednto tertiary;v buty1 bromidei subjecting.: the. eiuent of the,- hydrolorom,inationA,reactionv to. a; fractionalv distillation-,toI remove .theexcesshyolro-V gen1' bromide, subjecting the bottoms of,Y thecfirstf fractional, distillationv to f another. fractionaLdistillation; to remove the, residualY hydrocarbons overhead-andi,subjectngfthe bottomsl of this sec.- ond distillationto a third; distillationato; remove. the tertiary butyl bromide overheadr.ecycling the tertiary butyl bromide distillateto the preheating step, and recovering thefmethallyl brice mide from the bottoms of the lastifractionalcdiss- 35 tillation. Y i i 5. A process for the production-Offa-methallyl halide of the group consisting ofm'ethallyl'chloride and methallyl bromide which comprises presy heating a tertiary butyl halide of= the group` 40 consisting of tertiary butyl chloride-and-tertiarybutyl lorroirlgice,;4 which; tertiary; butyl; halide.: con: tainsitheame typehalogenatomas theo-desired mthallyl; halide; product. an-.dreacting the; rersultinsiproducttwitbia halogen,correspondingto; thee halogen. atom .ins the;` tertiary butyl. halide; maar :mlelrliQiOfsbll/Wen; 81h011ti2 tol; 94116138101, at.; tenglober;atuize.l aboyell C. Within; aboutg, second. tof31 seconda-.cooling the. reactiorrmixture d ntrodwina.itiintozaistreamiof hydrocarbonsi containmg;, isobutylene at',v such:` a: rate;Y that@l the; hydrogen halide; initheg-k reaction mixturei. and.'- tha addedkisobutylena arein amolerratiogof .besY

tween about Lto; andfi to,; v 1, ,reacting;the;reev

thoiliquidphae,atnagtempera- '55 halide of the group consisting of tertiary butylLV chloride and tertiary butyl bromide, reactinga molarexcess of thesaid preheated tertiarybutyl halide with Y a.A halogen corresponding to thehalo.` gen in the saiditertiary butylhalide at' a tem--l perature abovef300 C. for a periodbetween about .l second to 10 seconds, coolingA the: resulting mixture and'V mixing; itwithaliydrocarbon,stream containing isobuty-lene at such a` rate that the; hydrogen halide inthesaidfreaction'mix-ture and' theadded isobutylene-` `are in` amole ratio'. be-v tween about 1 to 1 and ktolyreacting;theref sulting mixturein theliquidphase atl a temperature below 300 G. butabove-80 G. fora-period.. not inI excess of 2,00 seconds wherebyv isobutylena is hydrohalogenated to tertiary butyl halidesub f jecting the eiluent ofthe hydrohalogenation re-V action to aseries offr 'distillationsf taseparaterout.

theA excess hydrogen'I halide, the' residuali hydrocartons. the, tenian/butyl hai'idand trie meth-l allyl halide, recycling the-,tertiary butyl halide:

to the preheat step',1and r'coverinthe methallyl halidefas the de's'iredprodiict.

HARRY n. CHENEY.

ALASBAIR- W. FAIRBAIRN. OHRISL. D AVIS.

References cited-m the eiofl this patent UNIT-n STATES PA'INTS;

Franca Nov3j2; 1943i. 

6. A PROCESS PRODUCING A METHALLYL HALIDE WHICH COMPRISES PREHEATING A TERITARY BUTYL HALIDE OF THE GROUP CONSISTING OF TERTIARY BUTYL CHLORIDE AND TERTIARY BUTYL BROMIDE, REACTING A MOLAR EXCESS OF THE SAID PREHEATED TERTIARY BUTYL HALIDE WITH A HALOGEN CORRESPONDING TO THE HALOGEN IN THE SAID TERTIARY BUTYL HALIDE AT A TEMPERATURE ABOVE 300* C. FOR A PERIOD BETWEEN ABOUT .1 SECOND TO 10 SECONDS, COOLING THE RESULTING MIXTURE AND MIXING IT WITH A HYDROCARBON STREAM CONTAINING ISOBUTYLENE AT SUCH A RATE THAT THE HYDROGEN HALIDE IN THE SAID REACTION MIXTURE AND THE ADDED ISOBUTYLENE ARE IN A MOLE RATIO BETWEEN ABOUT 1 TO 1 AND 4 TO 1, REACTING THE RESULTING MIXTURE IN THE LIQUID PHASE AT A TEMPERATURE BELOW 300* C. BUT ABOVE -80* C. FOR A PERIOD NOT IN EXCESS OF 200 SECONDS WHEREBY ISOBUTYLENE IS HYDROHALOGENATED TO TERTIARY BUTYL HALIDE, SUBJECTING THE EFFLUENT OF THE HYDROHALOGENATION REACTION TO A SERIES OF DISTILLATIONS TO SEPARATE OUT THE EXCESS HYDROGEN HALIDE, THE RESIDUAL HYDROCARBONS, THE TERTIARY BUTYL HALIDE AND THE METHALLYL HALIDE, RECYCLING THE TERTIARY BUTYL HALIDE TO THE PREHEAT STEP, AND RECOVERING THE METHALLYL HALIDE AS THE DESIRED PRODUCT. 